DESCRIPTION: The project examines the visual pathways involved in motion perception. Several methods will be used to asses whether an attribute such as color or stero is sensed by a low-level motion system or a high level attentional feature tracking system. In addition, opposing motion stimuli will test whether low level mechanisms represent a single class of motion detectors or several distinct classes. Tests of cortically color blind patients will analyze the motion response to color stimuli which do not rely on color sensations. The proposal will also evaluate the high level motion system based on attentive tracking - a pursuit system that involves attention rather than eye movements. The second half of the project will analyze the nature of the attentive mechanism, including whether attentive tracking is a real motion system in that it demonstrates predictive aspects. In addition, studies are proposed to measure the spatial resolution of attention during tracking.